Wave signaling system



-' Nov. 10,1925, "11561278 M. I. PUPIN WAVE SIGNALING SYSTEM Original Filed Feb. 4 191 Fig-.42

i1 AIIIIIIIIII 15 I6 I 5 y X; J) My)? INVENTOR I ATTORNEY Patented Nov. 1o,- 1925.

UNITED; 'S'I.ATES@ PATENT OFFICE.

111cm; 1-. Perm; or nonronx, commca xcor, ASSIGNOR TO wns'rmonousn mmc- 'rnrc AND MANUFACTURING column. or EAST rrr'rsnunon, rnmrszpvAmA, A

CORPORATION OF PENNSYLVANIA.

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appncanon and February 4, 1918,. Serial no. 215,294., Renewed January as, 1921. Serial m o To all whom it may concern:

' Be it known that I, MICHAEL I. Perm, a citizen of the United States, residin at Norfolk, in the county ofIgitchfield, tate 6- of Connecticut, have invented certain new and useful. Improvements in Wave; Signal-- ing Systems; and- I dohereby declare the following to be a full, clear, and exact. description of'the invention, such as w1ll enable l others skilled in the art to which it appertains to make and use the same. This invention isa receiver of high frequency' waves in which the phase distribution of the electrical forces produced by the 1 action of the-received waves is, so utilized that the receiveris rendered insensitivefor long waves without impairing its efiiciency forthereception of the short signaling waves.

2 In the accompanying drawing, Figure 1 is a diagrammatic representation of the essential elements in the construction of a crystal plate piezo-electric receiver. Fig. 2 is a diagram representing two piezo-electric receivers electrically connected to each other and to a Vacuum tube amplifier, in accordance with the' present invention. Fig. 3 is a diagram of a receiving system in which the I electrical waves produced by the action of all the sound waves on a piezo-electric receiver or the like, are led through a phase distribut ing device properly connected to a vacuum,

tube amplifier, in accordance with this invention.

' It is well known that when a piezo -electric crystal is subjected to-changes of pressurecorresponding changes of electrical potential will be produced on opposite faces of the crystal. The phenomenon, which is known as the piezo-electric eflect, has been made'use of in the detection of sound waves by caus-x' ing the received sound waves to vary the pressure uponthejcrystals, and observing the electrical potential variations produced Such receivers have practically no natural period of oscillation and are therefore aperiodic or deadbeat in character.

present invention, it will be assumed that 9 such dead beat receiving devices are em-- ployed, although, as will be understood by sorts oflsound receiving devices wherein the.

g In order toarrive at the simplest explanation of the its flat faces are parallel to the optical axis and perpendicularto anelectrical axis. .2

and 3 are two electrically conducting sheets,

as of tin foil, attached to these two flat faces as indicated. When a pressure is applied perpendicularly to these fiat faces by the piezo-electric .efl'ect a difference of potential between the two metal plates is produced, and when a tension is applied to the same two facesthen a difference of potential is produced which is'opposite to that produced by a pressure. A simple harmonic sound wave acting-upon the face of the plate will, therefore, produce. a simpleharmonic variation of the electrical potential between the two faces, as iswell known. This difference of potential is indicated by a vacuum tube repeater to which the metal plates are connected, and may be amplified and' detected. by vacuum tube amplifiers and detector circuits in several Well known ways.' It will be observed, howeYer, that such a receiver is sensitive to sound waves of-allfrequencies.

In Fig. 2,, an arrangement, in accordance with this invention, by which the receiver may be made selective with respect to sig- 'naling waves of high frequency, is shown.

In this figure, there are two equal'receiver's l and 4, of which 1 is provided,with the two metal plates 2, 3, and 4 is provided with the like metal plates 5, 6. By suitable electric connections the homologous metal plates 2 and 5 are connected to each other and the I other two homologous metal plates areconnected respectively to the grid and to the win 'of a vacuum tube repeater 7 of the usua construction, the wing circuit beinggrounded at 8, and being associated as throughthe transformer 9,-with a circuit 10 leading to amplifying or detecting devices. Assume thatplain soundwaves reach the receiver in thedirection indicated by the arrows. It is obvious that if-the two receivers Land 4 are homologously placed with respect'tothe incoming plain sound waves, then the homologous faces 2 and 5 will both develop, at' any givenfinstant, electricalioo - electromotive forces produced by stantially different tor and circuit connections so arranged that the the signaling sound waves are additively applied to the responsive device and the electromotive forces produced by all sound waves of subfrequency are differentially applied thereto. i

A receiver for a ploying high frequency sound waves comprising a crystal supported in the pathof the sound waves for producing an electromotive force of corresponding frequency, means for producing av corresponding electrolnotive'for'ce differing in phase from said first clectroinotive force, an electrical responsive device and connections for additively applying thereto the said electromethe forces.

4. The combination with an'input circuit carrying received currents of a predetermined frequency and other currents differing in frequency, of a helix having one terminal connected to one terminal of said input circuit, a condenser element connected to the other terminal of said input circuit and constituting, with said helix, a conduchaving distributed inductance and capacity, whereby there are one or more half-waves of the predetermined frequency within the full lengthof the helix, a pair of coupling means in operative relation to said conductor and spaced by substantially an odd multiple of one-half wave-length of the predetermined frequency, and an output circuit operatively associated with said pair of 7 coupling means.

' The combination with an input circuit carrying received currents of a predetermined frequency and other currents difien.

ing'in frequency, of a helix having one terminal connected to one terminal of said input circuit, a condenser element connected to the other terminal of said input circuit and constituting, with said helix, a conducsignaling system emput circuit associated with said coils whereby -the energy received from said currents of predetermined frequency is additive and the energy received from said other currents is differentially applied in said output circuit.

6. Means for selectively receiving compressional waves of a predetermined high frequency pressional waves into electrical waves, an

input circuit responsive to said transmitter,-

in a material medium, compris-i 111g a transmitter for converting said coman odd number of half wave-lengths of the predetermined frequency on said helix, and an output circuit including said coils in series whereby the secondary electromotive forces resulting from said high-frequency compressional waves are additive in said output circuit whereas the secondary electromotive-forces resulting from sound waves of ordinary frequency in said material medium are substantially said output circuit.

In testimony whereof I aflix' my signature.

MICHAEL .I. PUPIN.

oppositely applied in 

